textproduct: Rapid City

KEY MESSAGES

- Cooler today, but still above average.

- Gradually warming temperatures through the upcoming week.

- Mostly dry conditions, but light showers are possible if moisture can be found due to expected instability.

DISCUSSION

(Today Through Friday) Issued at 204 AM MST Sat Dec 20 2025

Latest upper level analysis shows quasi-zonal flow over the forecast area with a low over Manitoba and a weak trough extending through the western High Plains. At the surface, a cold front extends from a surface low in southwest Ontario, down through the Northern plains and into southeast Wyoming. Temperatures at 08Z range from the low 20s across northwestern South Dakota and portions of northeastern Wyoming, into the upper 30s across south central South Dakota.

Today will be colder, but still above seasonal averages, with highs ranging from the mid 30s across the Black Hills and northeastern Wyoming into the mid 40s in the eastern foothills and southwestern South Dakota. West northwest winds of 15 to 20 mph will be common over the South Dakota Plains, due to surface high pressure building into the area. Hi-res models indicate a 30-50% chance of wind gusts greater than 30 mph across northwestern South Dakota this morning.

For tonight, mostly clear skies and high pressure off to the east will allow temperatures to fall into the teens and upper 20s. Finer resolution models are picking up on a shortwave moving through the flow along a 700mb theta-e ridge after 10Z, producing some light snow over far southwestern South Dakota and northeastern Wyoming. Moisture appears to be limited until about 12Z Sunday morning, so have kept chances of light snow out of the forecast for now for the overnight period.

For Sunday, have added low pops to the forecast based on the hi-res models indicating light precip coinciding with the wave and instability. Moisture availability is the biggest question, but overall figured low pops were warranted based on the dynamics.

Messy zonal/southwest flow will promote above normal temperatures through much of Christmas week. A few weak disturbances may spark some light precipitation chances throughout the week; however, expect mostly dry and warm conditions to prevail.

AVIATION

(For the 12Z TAFS Through 12Z Sunday Morning) Issued At 412 AM MST Sat Dec 20 2025

VFR conditions are expected through the period.

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.